Within the medical supplies industry, there has been a long felt need to provide an inexpensive needle assembly consisting of a sterile hypodermic needle cannula retained in a holder and enclosed in a needle protector to physically protect the needle cannula during handling. Also the holder and protection alone or in combination with other portions of the needle assembly should completely enclose the needle cannula to maintain the sterility of the needle cannula during handling.
In general, these needle assemblies should allow easy removal of the needle protector before use of the needle cannula. Also, the holder for the needle cannula should allow the user to establish a fluidly communicating connection between the needle cannula and a medical device such as a syringe.
In addition to the general requirements, users of needle cannula such as doctors and other medical personnel look for particular characteristics, such as a definitive way to determine the integrity of the sterile seal provided by the needle assembly immediately prior to removal of the protector for use, and a clean neat appearance both before and after removal of the protector. Further, due to the large number of needle cannulas employed by medical businesses, a needle assembly needs to be able to be inexpensively produced.
One general type of needle protector assembly, as disclosed in U.S. Pat. Nos. 3,523,530, 4,435,177 and 4,657,535, consists of a needle cannula having a cylindrical base or holder for retaining the needle and a hollow tubular protector which encloses an exposed portion of the needle cannula. The exposed portion extends from the holder up to and including the pointed tip. The holder and protector, however, are separately molded pieces and require an assembly step to form the needle assembly. After assembly of the separately molded pieces, the protector is bonded in a fluid-tight manner to the holder as known in the art, such as by either a heat sealing process or an adhesive. A drawback of this type of needle assembly is that the two separate molding operations and assembly step increase the cost of the needle assembly. A second drawback is that as the size of the needle cannula becomes smaller it requires greater effort and therefore more expense to establish a sealing bond between the protector and holder. Also because the bond is beneath the overlapping segment of the protector, it is difficult for medical personnel to inspect the bond prior to removal of the protector to insure the sterile seal has been maintained during handling. Finally the rearward end of the holder is open and therefore to sterilely seal the needle cannula, the holder must be bonded to a medical device or the entire needle assembly must be packaged in an additional enclosure.
A second general type of needle cover assembly, an embodiment of which is disclosed in U.S. Pat. No. 4,091,811, includes an inner sleeve which is inserted over the pointed forward end of the needle cannula. An outer sleeve retains the rearward end of the needle, extends around the inner sleeve and ends in an open end forward of the pointed end of the needle. A plug is then employed to seal the open end. This type of needle assembly also suffers the drawback of requiring three separate pieces to be molded and assembled for the needle cover to function properly. The assembly step adds expense to the manufacture of this needle cover assembly. This device also has a holder having an open rearward end and therefore requires a separate enclosure to sterilely seal the needle cannula.
Thus there is a need for a needle assembly which physically protects and preserves the sterility of the needle cannula during handling and which eliminates the separate molding operations of the component parts and an assembly of the same.
There is a further need for a needle assembly which completely encloses the needle cannula thus eliminating a separate enclosure to supply sterile protection.
There is also a need for a needle assembly which allows the user to easily determine that the sterile integrity of the needle cannula has been preserved until it becomes necessary to remove the protector.
There is an additional need for a method of manufacturing a needle assembly in which the needle cannula holder and protector are formed as a unitary piece which completely encloses the needle cannula in a single step operation. Such a method would reduce the cost of manufacturing the needle assembly and eliminate the problems associated with bonding a holder to a separate protector.